ref: 3579757291db68f8e17a376476454996b7961bd7
dir: /sys/src/ape/lib/ap/plan9/ctime.c/
/* * This routine converts time as follows. * The epoch is 0000 Jan 1 1970 GMT. * The argument time is in seconds since then. * The localtime(t) entry returns a pointer to an array * containing * * seconds (0-59) * minutes (0-59) * hours (0-23) * day of month (1-31) * month (0-11) * year-1970 * weekday (0-6, Sun is 0) * day of the year * daylight savings flag * * The routine gets the daylight savings time from the environment. * * asctime(tvec)) * where tvec is produced by localtime * returns a ptr to a character string * that has the ascii time in the form * * \\ * Thu Jan 01 00:00:00 1970n0 * 01234567890123456789012345 * 0 1 2 * * ctime(t) just calls localtime, then asctime. */ #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <time.h> #include <unistd.h> #include <string.h> static char dmsize[12] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }; /* * The following table is used for 1974 and 1975 and * gives the day number of the first day after the Sunday of the * change. */ static int dysize(int); static void ct_numb(char*, int); static void readtimezone(void); static int rd_name(char**, char*); static int rd_long(char**, long*); #define TZSIZE 150 static struct { char stname[4]; char dlname[4]; long stdiff; long dldiff; long dlpairs[TZSIZE]; } tz; char* ctime(const time_t *t) { return asctime(localtime(t)); } struct tm* gmtime_r(const time_t *timp, struct tm *result) { int d0, d1; long hms, day; time_t tim; tim = *timp; /* * break initial number into days */ hms = tim % 86400L; day = tim / 86400L; if(hms < 0) { hms += 86400L; day -= 1; } /* * generate hours:minutes:seconds */ result->tm_sec = hms % 60; d1 = hms / 60; result->tm_min = d1 % 60; d1 /= 60; result->tm_hour = d1; /* * day is the day number. * generate day of the week. * The addend is 4 mod 7 (1/1/1970 was Thursday) */ result->tm_wday = (day + 7340036L) % 7; /* * year number */ if(day >= 0) for(d1 = 70; day >= dysize(d1); d1++) day -= dysize(d1); else for (d1 = 70; day < 0; d1--) day += dysize(d1-1); result->tm_year = d1; result->tm_yday = d0 = day; /* * generate month */ if(dysize(d1) == 366) dmsize[1] = 29; for(d1 = 0; d0 >= dmsize[d1]; d1++) d0 -= dmsize[d1]; dmsize[1] = 28; result->tm_mday = d0 + 1; result->tm_mon = d1; result->tm_isdst = 0; return result; } struct tm* gmtime(const time_t *timp) { static struct tm xtime; return gmtime_r(timp, &xtime); } struct tm* localtime_r(const time_t *timp, struct tm *result) { struct tm *ct; time_t t, tim; long *p; int dlflag; tim = *timp; if(tz.stname[0] == 0) readtimezone(); t = tim + tz.stdiff; dlflag = 0; for(p = tz.dlpairs; *p; p += 2) if(t >= p[0]) if(t < p[1]) { t = tim + tz.dldiff; dlflag++; break; } ct = gmtime_r(&t, result); ct->tm_isdst = dlflag; return ct; } struct tm* localtime(const time_t *timp) { static struct tm xtime; return localtime_r(timp, &xtime); } char* asctime_r(const struct tm *t, char *buf) { char *ncp; strcpy(buf, "Thu Jan 01 00:00:00 1970\n"); ncp = &"SunMonTueWedThuFriSat"[t->tm_wday*3]; buf[0] = *ncp++; buf[1] = *ncp++; buf[2] = *ncp; ncp = &"JanFebMarAprMayJunJulAugSepOctNovDec"[t->tm_mon*3]; buf[4] = *ncp++; buf[5] = *ncp++; buf[6] = *ncp; ct_numb(buf+8, t->tm_mday); ct_numb(buf+11, t->tm_hour+100); ct_numb(buf+14, t->tm_min+100); ct_numb(buf+17, t->tm_sec+100); if(t->tm_year >= 100) { buf[20] = '2'; buf[21] = '0'; } ct_numb(buf+22, t->tm_year+100); return buf; } char* asctime(const struct tm *t) { static char cbuf[30]; return asctime_r(t, cbuf); } static dysize(int y) { if((y%4) == 0) return 366; return 365; } static void ct_numb(char *cp, int n) { cp[0] = ' '; if(n >= 10) cp[0] = (n/10)%10 + '0'; cp[1] = n%10 + '0'; } static void readtimezone(void) { char buf[TZSIZE*11+30], *p; int i; memset(buf, 0, sizeof(buf)); i = open("/env/timezone", 0); if(i < 0) goto error; if(read(i, buf, sizeof(buf)) >= sizeof(buf)) goto error; close(i); p = buf; if(rd_name(&p, tz.stname)) goto error; if(rd_long(&p, &tz.stdiff)) goto error; if(rd_name(&p, tz.dlname)) goto error; if(rd_long(&p, &tz.dldiff)) goto error; for(i=0; i<TZSIZE; i++) { if(rd_long(&p, &tz.dlpairs[i])) goto error; if(tz.dlpairs[i] == 0) return; } error: tz.stdiff = 0; strcpy(tz.stname, "GMT"); tz.dlpairs[0] = 0; } static rd_name(char **f, char *p) { int c, i; for(;;) { c = *(*f)++; if(c != ' ' && c != '\n') break; } for(i=0; i<3; i++) { if(c == ' ' || c == '\n') return 1; *p++ = c; c = *(*f)++; } if(c != ' ' && c != '\n') return 1; *p = 0; return 0; } static rd_long(char **f, long *p) { int c, s; long l; s = 0; for(;;) { c = *(*f)++; if(c == '-') { s++; continue; } if(c != ' ' && c != '\n') break; } if(c == 0) { *p = 0; return 0; } l = 0; for(;;) { if(c == ' ' || c == '\n') break; if(c < '0' || c > '9') return 1; l = l*10 + c-'0'; c = *(*f)++; } if(s) l = -l; *p = l; return 0; }